Columbus crossed the ocean and other questions about explorers / I wonder why．Columbus crossed the ocean and other questions about explorers / I wonder why Columbus crossed the ocean and other questions about explorers Romans wore togas and other questions about Rome / Horses wear shoes and other questions about horses / How does a seed sprout? and other questions about plants Leaves change color and other questions about plants Zippers have teeth and other questions about inventions / I wonder why snakes shed their skin :: and other questions about reptiles / I wonder why snakes shed their skin and other questions about reptiles